My Mom was Grammy, which I really liked, but it was in use...
My son asked me what I wanted my grandma name to be. I took some time and thought about it. Then I let him know that I would like to be called "Oma" or "Gma" as they sound loving and friendly to me. I also told him that I was already used to either of those names, since he and his siblings so often addressed me as "Gee, Ma,..." or "Oh, Ma, ..." His response to me started with."Gee, Ma" I stopped him and said "I rest my case."
He and his then girlfriend chose "Oma". Later, my Mother told me that "Oma" was the German Grandmother name.
It is the name I most love to hear. It means my grandchildren are nearby!